In recent years, along with improvements in performance and size reduction of image pickup devices, digital apparatuses with an image input function each including an imaging optical device, such as a mobile phone and a portable information terminal, have been coming into widespread use. This has led to a demand that an imaging lens system incorporated in an imaging optical device also be further improved in performance and size reduction and have an increased angle of view. Since it is not easy to eliminate various types of aberration over a wide angle of view, however, the more an angle of view is increased, the more difficult it becomes to correct aberration of an imaging lens system. Meanwhile, among various types of aberration, curvature of field occurs due to a deviation between an imaging flat surface and an image surface, and, therefore, by setting an imaging surface to have the same shape as that of an image surface, it is possible to reduce a burden of correcting this type of aberration on a lens system. From this standpoint, for the purpose of reducing curvature of field, each of Patent Documents 1 and 2 proposes a solid-state image pickup device having a curved imaging surface.